1. Field of the Invention
The present invention relates to a pneumatic tire that is improved in drainage performance while maintaining uneven wear resistance.
2. Description of the Background Art
There is a known pneumatic tire with a block pattern at a tread portion in which a plurality of blocks are formed by a plurality of circumferentially extending longitudinal grooves and a plurality of axially extending lateral grooves. In recent years, such a pneumatic tire has been improved in uneven wear resistance by increasing pattern rigidity of the blocks.
In general, pattern rigidity can be effectively increased by reducing widths and depths of longitudinal grooves and lateral grooves. However, if longitudinal grooves and lateral grooves are made smaller in width and depth, groove capacity is reduced to deteriorate drainage performance. In particular, shoulder lateral grooves connected to tread edges contribute considerably to drainage performance, and therefore simply decreasing the groove depth leads to significant deterioration of drainage performance. Thus, there is a trade-off relation between improvement of drainage performance and assurance of uneven wear resistance, and it is difficult to ensure compatibility between the two.